Tire manufacturing plant is generally divided into a material storage zone, a green tire formation zone for forming green tires from materials supplied from the material storage zone, a vulcanization zone for vulcanizing the green tires, and an inspection and discharge zone for inspecting and discharging the vulcanized tires. In the green tire formation zone, conventionally, green tires are formed on a green tire formation line schematically shown in FIG. 14.
The green tire formation line includes a cylindrical formation drum (a), a shaping drum (b), and a tread formation drum (c). A cylindrical carcass body (ta) is formed by winding an inner liner rubber (t1) and a carcass ply (t2) on an outer peripheral surface of the formation drum (a). Reference numerals (d1) and (d2) denote conveyor-like servicers that supply the inner liner rubber (t1) and the carcass ply (t2), respectively. Bead cores (t3) with bead apex rubber are externally inserted into the cylindrical carcass body (ta). Reference numeral (d3) denotes a servicer that supplies the bead cores (t3). The cylindrical carcass body (ta) into which the bead cores (t3) are externally inserted is transferred from the formation drum (a) to the shaping drum (b) using a transferor (transfer equipment) not shown.
A cylindrical tread ring (tc) is formed by winding a belt ply (t4), a band ply (t5), and a tread rubber (t6) on an outer peripheral surface of the tread formation drum (c). Reference numerals (d4) to (d6) denote conveyor-like servicers that supply the belt ply (t4), the band ply (t5), and the tread rubber (t6), respectively. The tread ring (tc) is transferred using a transferor (transfer equipment) not shown from the tread formation drum (c) and held at the radial outside of the shaping drum (b). Reference numeral (d7) denotes a servicer that supplies a side wall rubber (t7) and the like.
At the shaping drum (b), the cylindrical carcass body (ta) is bulged in a toroidal shape between the bead cores (t3), (t3), and the bulged portion is joined to the inner peripheral surface of the tread ring (tc) to form a green tire. The green tire is removed from the shaping drum (b) and then carried to the vulcanization zone for vulcanization process.
On such a conventional green tire formation line as described above, various tire constituent members such as the inner liner rubber (t1), the carcass ply (t2), the bead core (t3), the belt ply (t4), the band ply (t5), the tread rubber (t6), the side wall rubber (t7) are processed in advance off the line to various widths, various cross-section shapes, or various cord angles according to a tire size. Thus, the conventional green tire formation line is suited for mass production of tires of one size.
On the other hand, the pre-processed tire constituent members are temporarily stored as semi-finished members in the material storage zone. The kinds of members increase in number according to tire sizes. This results in expansion of space for the material storage zone.
In addition, separate pre-processing lines are needed to pre-process the tire constituent members. Since the tire constituent members are wide, the servicers (d1) to (d7) for supplying them are also increased in size. This also brings about expansion of space for the green tire formation zone.
Since green tires of one size are mass-produced, the vulcanization process cannot keep up with the green tire production. Accordingly, a separate green tire storage space is needed to temporarily store green tires to be vulcanized. It is also necessary to increase the number of vulcanization molds in keeping with the mass production. The kinds of vulcanization molds increase in number even for tires of the same model according to tire sizes. This requires a separate space for storage of vulcanization molds of many sizes not used at present.
As a result, when a tire manufacturing plant is to be installed, the site space for the plant needs to be at least 25 m wide and 170 m long or more, which becomes a large hindrance for installation of the plant.
Patent Document 1 shown below can be exemplified as a document describing a prior technique related to a green tire formation line.